Conventional pharmaceutical preparations for treatment of various skin ulcers include ointments containing antibiotics, antibacterial agents, or enzymes; skin lotions; water-absorbing powders of high polymers; wound protectives; and the like. For particular use in the treatment of skin ulcers with exudate, ointments having water-absorbing and drying properties are commonly employed.
On the other hand, therapeutic effects of adenosine 3',5'-cyclic phosphate (hereinafter referred to as cyclic AMP) derivatives on various skin ulcers have been elucidated as disclosed in JP-A-63-107935 (the term "JP-A" as used herein means an "unexamined published Japanese patent application").
Ointment bases which are believed most effective for the preparations of the cyclic AMP derivatives in the treatment of skin ulcers are of the type having water-absorbing and drying properties. However, these ointment bases contain therein a trace amount of water. If the cyclic AMP derivative is dispersed or dissolved in such ointment bases, the cyclic AMP derivatives are gradually hydrolyzed, thus becoming ineffective through long-term preservation.